How to set a property observer on system variable

Question

I have the following variable: private var screenWidth = UIScreen.mainScreen().bounds.width

I was wondering how I could set a property observer on it? Or get the latest version of it when it updates?

Answer 1

There's no general approach that works for everything. You can often use Key-Value Observing. In this case, you can listen for the UIScreenModeDidChangeNotification notification.